A pulse code modulation system is known from German Patent Publication DE 31 13 397 C2 and U.S. Pat. No. 4,491,869, in which a digital signal is passed through a recording or transmission channel having a high-pass characteristic. In this system the bandwidth of the analog signal on which the digital signal is based is limited to the extent that the highest frequencies contained in the band-limited analog signal are smaller than half of the sampling frequency which is used for analog-to-digital conversion. The digital signal is inverted from sample to sample and thereafter a code is established by which within a word the number of bits having one of the logic levels has a linear dependence on the corresponding value of the analog signal. From German Patent DE 28 28 219 A1 and U.S. Pat. No. 4,310,860, a method for transmitting digitally coded signals is known in which the stream of individual data words of a given data stream is subdivided into sequences with and without d.c. component and the sequences having a d.c. component are replaced by sequences without a d.c. component.